1. Technical Field
The present invention relates to a vehicle power assist steering system. In particular, the present invention relates to a method of forming the mounting features of a housing of an electric power assist steering system.
2. Description of the Prior Art
A known type of vehicle power assist steering system includes a ball nut for transmitting force between a steering member and an electric assist motor. Upon actuation of the electric motor, the ball nut is driven to rotate relative to the steering member. The rotational force of the ball nut is transmitted to the steering member to drive the steering member axially. Axial movement of the steering member effects turning movement of the steerable wheels of the vehicle.
The steering system typically includes a housing that contains most of the components of the steering system. The housing is cast from a metal, such as aluminum. The housing, as cast, can include one or more mounting features, such as tabs or mounting feet, for mounting the steering system to the vehicle body.
The present invention is a method of making a steering assembly for turning steerable wheels of a vehicle in response to rotation of a steering wheel of the vehicle. The method comprises the steps of:
providing a pinion;
providing a steering member that is movable axially to effect turning movement of the steerable wheels of the vehicle, the steering member having a rack portion for engagement with the pinion and an externally threaded screw portion;
providing a ball nut cooperating with the screw portion to move the steering member axially upon rotation of the ball nut;
providing an electric motor comprising a stator and a rotor drivingly connected to the ball nut to rotate the ball nut when the motor is energized;
said step of providing a steering member comprising providing a steering member having an additional portion projecting from the ball nut for connection with a steerable wheel of the vehicle; and
cold forming a metal housing having a generally cylindrical main body portion for enclosing and supporting the electric motor and the ball nut and having a generally cylindrical outboard housing portion for enclosing the outboard portion of the steering member;
said cold forming step comprising cold forming a metal housing having a plurality of mounting feet formed with the outboard portion of the housing and projecting from the outboard portion of the housing for mounting the steering assembly to the vehicle;
enclosing and supporting the electric motor and the ball nut in the main body portion of the metal housing; and
enclosing the additional portion of the steering member in the outboard portion of the metal housing.